Random restarts

[A_Google_user]

Hi all, I recently got the s21 ultra.. what a great phone 👍  However, about 2 weeks ago it started to restart itself at random times of the day/night which is annoying, especially if I'm on a call or filling in an online form for something!  Is anyone else having this issue and do you know how to stop it from doing this?

[DaveyxG]

Go to device care click the 3 dots top right of the screen then click automotion to check if auto restart at set times is turned on if it is turn it off

[BandOfBrothers]

Thats not good @A_Google_user 

As a process of elimination can you put your phone in Safe Mode.

https://www.samsung.com/uk/support/mobile-devices/how-to-start-my-galaxy-device-in-safe-mode/ 

This will help to determine if an app is causing this.

If it continues in safe mode then clear the phones system cache files.

Clear your System File Cache vai the instructions in the Samsung Link. You may need to hook upto a computer or insert your headphones to get to the recovery menu. https://www.samsung.com/uk/support/mobile-devices/how-do-i-clear-the-cache-on-my-device/ 

As a last resort back up and factory reset.

A Samsung Experience Store  / Samsung Service Centre can take a look at your phone.

[A_Google_user]

Cheers, tried that a few days ago but it was off.

[A_Google_user]

Thanks.. I put it in safe mode yesterday and it seems to have sorted it out, no restarts for about 16 hours now!! When I came out of safe mode it had removed my theme, I think maybe it was that causing the issue 🤔

[BandOfBrothers]

Yes that's sounds like the culprit.

Safe Mode is such a good troubleshooting tool.

[A_Google_user]

Update: nope that hasn't fixed it, its still resetting several times day and night!

[nico81arg]

Same problem here... dealing with customer service it doesn't help... the options so far are send the phone for 2+ weeks to repair (who needs a phone in 2021 anyway) or call a store(who never answer the phone) to have the phone repaired in store... BTW the website to book the repair doesn't work either... 🙃

[A_Google_user]

I was lucky enough to still be within the 30 day purchase period so have now changed my handset for a new one.. fingers crossed this ones ok (so far so good)🤞 I tried absolutely everything with the other 1 and nothing worked. It started resetting all my ringtones and other settings back to default everytime it restarted which was really p*ssing me off!
I even messaged Samsung on twitter and they wouldn't acknowledge the issue, even though its well documented in all the forums I've looked in! (Just wish I'd looked in them 1st before buying it!)

[purplesquirrel]

Hi guys I just wanted to mention that something similar happened to my S21. And in my case, it was related to the way I charged my phone. So, I had this very long zoom meeting and my phone was dying so I plugged my phone to a USB port extender plugged to my laptop. My phone was charging super slow probably for an hour or two. After that the random shutting down started nonstop. I restarted, clean the phone app cache, nothing worked.  I found the solution: Just properly charge your phone! So I just turned my phone off and plugged to my Anker fast charger  and let it plugged until it hit the 85% (I have that option on to extend the battery life) And this fixed the problem . Hope it helps! https://www.amazon.com/gp/product/B08M9M2V7X/ref=as_li_tl?ie=UTF8&camp=1789&creative=9325&creativeAS...